Blizzard, there is currently a bug with Frost Bomb (and or spell reflect)that allows Mages to take NO damage from Frost Bomb when it is reflected by any sort of spell reflect.

Warrior Spell Reflect, Monk Diffuse Magic, etc.Here is a link to a video of a Mage taking damage from his own Frost Bomb detonation and then being healed back up to the percentage of health he was at before the Frost Bomb detonates once he takes damage from any source after the detonation.

There is no game mechanic that makes it so Mages are not supposed to take damage from Frost Bomb reflections. Please hot-fix this Blizzard. This bug has actually been in the game for quite a while and no one has addressed it.

You can see the forum post here, please comment on it so it becomes noticed.